1. Field of the Invention
The present invention relates to a communication system, and more particularly, a double ring-type local area network (LAN) system using time division multiple access (TDMA).
2. Description of the Related Art
In a prior art double ring-type CAN system, a plurality of nodes are connected by a counterclockwise signal flow transmission line and a clockwise signal flow transmission line that provide distinct communication paths between each node in opposite directions. When a fault occurs in one of the transmission lines, data traveling between nodes on one communication path may be switched to travel between the nodes on the other communication path. On the other hand, when the fault which occurred in the above-mentioned transmission line recovers, the data switched to the other communication path may be switched back to the original communication path. This will be explained later in detail.
Thus, when the above-mentioned switching occurs in the communication paths, the continuity of signal transmission may be distrusted due to the difference in transmission delay time before and after the switching. Therefore, although the prior art ring-type LAN system is applicable to discrete communications such as packet communications, the prior art ring-type LAN system cannot be applied to complications over dedicated lines, since the quality of transmission is degraded.